Electronic electric meter for networked meter reading

ABSTRACT

An electronic electric meter for use in a networked automatic meter reading environment. The electric meter retrofits into existing meter sockets and is available for new meter installations for both single phase and three phase electric power connections. The meter utilizes an all electronic design including a meter microcontroller, a measurement microcontroller, a communication microcontroller and spread spectrum processor, and a plurality of other communication interface modules for communicating commodity utilization and power quality data to a utility. The electric meter utilizes a modular design which allows the interface modules to be changed depending upon the desired communication network interface. The meter measures electricity usage and monitors power quality parameters for transmission to the utility over a two-way 900 MHz spread spectrum local area network (LAN) to a remotely located gateway node. The gateway node transmits this data to the utility over a commercially available fixed wide area network (WAN). The meter also provides direct communication to the utility over a commercially available network interface that plugs into the meter&#39;s backplane or bus system bypassing the local area network communication link and gateway node.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation of prior filed co-pending U.S.patent application Ser. No. 10/319,856, filed Dec. 13, 2002, which is acontinuation of U.S. application Ser. No. 09/242,792, filed Feb. 23,1999, and now issued as U.S. Pat. No. 6,538,577.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to apparatus for measuring usage ofa commodity. More particularly, the invention relates to an electronicelectric meter for measuring consumption of electricity andcommunicating that usage data and other power information to a utilityover a two-way wireless local area network (LAN) to a remotely locatedgateway node that transmits the data over a two-way fixed common carrierwide area network (WAN), or communicating that data directly to theutility, over a commercially available two-way data communicationnetwork.

[0003] Commodity usage is conventionally determined by utility companiesusing meters that monitor subscriber consumption. The utility serviceprovider typically determines the subscriber's consumption by sending aservice person to each meter location to manually record the informationdisplayed on the meter dial. The manual reading is then entered into acomputer which processes the information and outputs a billing statementfor the subscriber. However, it is often difficult for the serviceperson to access the meter for reading, inspection and maintenance. Whenaccess to a meter is not possible, billings are made on the basis ofestimated readings. These estimated billings often lead to customercomplaints.

[0004] Currently available electric meters such as watt-hour meters workwell for their intended purpose, but they must be manually read. Thismakes it difficult to cost effectively measure electricity usage foreach user to promote fair billing and encourage conservation. Manualreading of electric meter is highly labor intensive, inefficient andvery expensive. Therefore, there has been a strong interest on the partof utility companies to take advantage of modern technology to reduceoperating costs and increase efficiency by eliminating the necessity formanual readings.

[0005] Many attempts have been made in recent years to develop anautomatic meter reading system for electric meters which avoid the highcosts of manual meter reading. However, most of these prior art systemshave achieved little success. For automatic or remote meter reading, atransducer unit must be used with the meters to detect the output ofsuch meters and transmit that information back to the utility.

[0006] Various types of devices have been attached to utility meters inan effort to simplify meter reading. These devices were developed totransfer commodity usage data over a communication link to a centrallylocated service center or utility. These communication links includedtelephone lines, power lines, or a radio frequency (RF) link.

[0007] The use of existing telephone lines and power lines tocommunicate commodity usage data to a utility have encounteredsignificant technical difficulties. In a telephone line system, themeter data may interfere with the subscriber's normal phone lineoperation, and would require cooperation between the telephone companyand the utility company for shared use of the telephone lines. Atelephone line communication link would also require a hard wireconnection between the meter and the main telephone line, increasinginstallation costs. The use of a power line carrier (PLC) communicationlink over existing power lines would again require a hard wireconnection between the meter and the main power line. Anotherdisadvantage of the PLC system is the possibility of losing data frominterference on the power line.

[0008] Meters have been developed which can be read remotely. Suchmeters are configured as transducers and include a radio transmitter fortransmitting data to the utility. These prior art systems required themeter to be polled on a regular basis by a data interrogator. The datainterrogator may be mounted to a mobile unit traveling around theneighborhood, incorporated within a portable hand-held unit carried by aservice person, or mounted at a centrally located site. When the meteris interrogated by a RF signal from the data interrogator, the meterresponds by transmitting a signal encoded with the meter reading and anyother information requested. The meter does not initiate thecommunication.

[0009] However, such prior art systems have disadvantages. The firstdisadvantage is that the device mounted to the meter generally has asmall transceiver having a very low power output and thus a very shortrange. This would require that the interrogation unit be in closeproximity to the meters. Another disadvantage is that the deviceattached to the meter must be polled on a regular basis by the datainterrogator. The device attached to the meter is not able to initiate acommunication. The mobile and hand-held data interrogators are oflimited value since it is still necessary for utility service personnelto travel around neighborhoods and businesses to remotely read themeters. It only avoids the necessity of entering a residence or otherbuilding to read the meters. The systems utilizing a data interrogatorat fixed locations still have the disadvantages of low power output fromthe devices attached to the meters, and requiring polling by the datainterrogator to initiate communication.

[0010] Therefore, although automatic meter reading systems are known inthe prior art, the currently available automatic meter reading systemssuffer from several disadvantages, such as low operating range andcommunication reliability. Thus, it would be desirable to provide anelectronic electric meter to retrofit into existing meter sockets or fornew installations that enables cost effective measurement of electricityusage by a consumer. It would also be desirable to have an electricmeter that is capable of providing automatic networked meter reading.

SUMMARY OF THE INVENTION

[0011] An object of the present invention is to provide an integratedfully electronic electric meter that retrofits into existing metersockets and is compatible with current utility operations.

[0012] Another object of the invention is to provide an electronicelectric meter that communicates commodity utilization data and powerquality information to a utility over a two-way wireless spread spectrumlocal area network to a gateway node that transmits the data over atwo-way fixed common carrier wide area network, or communicates the datadirectly to the utility over a commercially available two-way datacommunication network.

[0013] A further object of the invention is to provide a gateway nodefor receiving commodity utilization data and power quality informationfrom the electric meter and transmitting that data to a utility serviceprovider over a commercially available fixed common carrier wide areanetwork.

[0014] Yet another object of the invention is to provide an electronicelectric meter that communicates commodity utilization data and powerquality information upon interrogation by a communication node, atpreprogrammed scheduled reading times, and by spontaneous reporting oftamper or power outage conditions.

[0015] Yet another object of the invention is to provide an electronicelectric meter that is of a modular construction to easily allow anoperator to change circuit boards or modules depending upon the desireddata communication network.

[0016] The present invention is a fully electronic electric meter forcollecting, processing and transmitting commodity utilization and powerquality data to a utility service provider.

[0017] The electronic electric meter is of a modular design allowing forthe removal and interchangeability of circuit boards and modules withinthe meter. All of the circuit boards and modules plug into a commonbackplane or busing system.

[0018] The electric meter is able to communicate commodity utilizationdata and power quality information to a utility over a local areanetwork (LAN) or a wide area network (WAN). A radio frequency (RF)transceiver located within the meter creates a LAN link between themeter and a gateway node located remotely from the meter. This LANutilizes a 900 MHz spread spectrum communication technique fortransmitting commodity utilization data and power quality informationfrom the meter to the gateway node, and for receiving interrogationsignals from the gateway node.

[0019] The electric meter is also able to communicate directly with theutility through the variety of commercially available communicationnetwork interface modules that plug into the meter's backplane or bussystem. For example, these modules might include a narrowband personalcommunication services (PCS) module or a power line carrier (PLC)module. For these modules, a gateway node is not necessary to completethe communication link between the meter and the utility.

[0020] The gateway node is located remotely from the meter to completethe local area network. The gateway node is also made up of four majorcomponents. These components include a wide area network interfacemodule, an initialization microcontroller, a spread spectrum processorand a RF transceiver. The gateway node is responsible for providinginterrogation signals to the meter and for receiving commodityutilization data from the interface management unit for the local areanetwork. However, the gateway node also provides the link to the utilityservice provider over a commercially available fixed two-way commoncarrier wide area network.

[0021] The RF transceiver of the gateway node transmits interrogationsignals from the utility or preprogrammed signals for scheduled readingsto the electric meter, and receives commodity utilization data in returnfrom the meter for transmission to the utility over the wide areanetwork. The spread spectrum processor is coupled to the RF transceiverand enables the gateway node to transmit and receive data utilizing thespread spectrum communication technique. The WAN interface module iscoupled to the spread spectrum processor and transmits data to and fromthe utility service provider over any commercially available wide areanetwork that is desired. A different WAN interface module can be usedfor each different commercially available wide area network desired. Theinitialization microcontroller is interposed between the interfacemodule and the spread spectrum processor for controlling operation ofthe spread spectrum processor and for controlling communication withinthe gateway node.

[0022] Meter reading, meter information management and networkcommunications are all controlled by two-way system software that ispreprogrammed into the electric meter's memory during manufacture andinstallation. The software enables an operator to program utilityidentification numbers, meter settings and readings, units of measureand alarm set points.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0023]FIG. 1 is a perspective view of an electronic electric meter inaccordance with the present invention;

[0024]FIG. 2 is a cross-sectional view of the internal structure of theelectric meter shown in FIG. 1;

[0025]FIG. 3 is a block diagram of the electric meter circuitry;

[0026]FIG. 4 is a front elevational view of a gateway node;

[0027]FIG. 5 is a schematic view of the electric meter interfacing witha remote gateway node and a utility service provider, creating anetworked automatic meter reading data communication system;

[0028]FIG. 6 is a flow diagram of the automatic meter reading datacommunication system shown in FIG. 5;

[0029]FIG. 7 is a block diagram of the gateway node circuitry;

[0030]FIG. 8 is a functional block diagram of the automatic meterreading data communication system of FIGS. 5 and 6;

[0031]FIG. 9A is a flow diagram of the WAN handler portion of the datacommunication system of FIG. 8;

[0032]FIG. 9B is a flow diagram of the message dispatcher portion of thedata communication system of FIG. 8;

[0033]FIG. 9C is a flow diagram of the RF handler portion of the datacommunication system of FIG. 8;

[0034]FIG. 9D is a flow diagram of the scheduler portion of the datacommunication system of FIG. 8; and

[0035]FIG. 9E is a flow diagram of the data stores portion of the datacommunication system of FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

[0036] Electronic Electric Meter

[0037]FIGS. 1 and 2 show a fully integrated, self-contained electronicelectric meter 10 for measuring electricity usage and monitoring powerquality. The meter 10 is operable for both single phase and three phaseelectric power installations. The meter 10 includes a top cover 12attached to a meter base 14. Extending outwardly from the meter base 14is a mounting frame 16 and a pair of terminals 18, 20. The meter 10easily retrofits into existing meter sockets by insertion of terminals18, 20 into the sockets and interlocking the mounting frame to securethe meter in place. The terminals 18, 20 complete the connection betweenthe electric power line and the meter 10. The meter 10 further includesa liquid crystal display 22 for displaying meter readings and settings,units of measure and status conditions. The top cover 12 includes arectangular opening 24 for the LCD 22. A rectangularly shapedtransparent piece of glass or plastic covers the rectangular opening 24for viewing LCD 22.

[0038] As shown in FIG. 2, the fully electronic, self-contained, modularelectric meter 10 includes several electronic sub-assemblies. Thesub-assemblies include a power transformer 32, a current transformer 34,a power/meter circuit board 36, an interface management unit circuitboard 38, a RF transceiver sub-assembly 40, an LCD sub-assembly 42, anda variety of commercially available plug in network modules, such as anarrowband personal communication services (PCS) module 41 and a powerline carrier (PLC) module 43.

[0039] All of the circuit boards and modules plug into a commonbackplane or busing system (not shown) providing a modular constructionallowing for interchangeability of circuit boards and modules dependingon the data communication network desired. While the meter 10 is shownas an electric meter, the meter 10 can also be configured to measureother physical characteristics such as water and gas.

[0040] Circuitry of Electronic Electric Meter

[0041]FIG. 3 shows a block diagram of the electric meter's internalcircuitry. The meter 10 is powered directly from the electric power linecoming through terminals 18, 20 and into power transformer 32 to providethe DC power required of the meter circuitry. Back up battery power 44is provided in case of electrical power outages.

[0042] The electrical power flowing through terminals 18 and 20 issensed by voltage interface transducer 46 and current interfacetransducer 48. The accumulated pulse totalization from transducers 46and 48 is input into meter microcontroller 50 which interprets theelectrical signal data received from transducers 46 and 48. Theprocessed electrical signal data is then sent through a level translator52 to condition the signals for the required input into measurementmicrocontroller 54. Measurement microcontroller 54 performs additionalcalculations on the electrical signals received from metermicrocontroller 50 and prepares them for output to the LCD 22 or anappropriate communication network. Meter microcontroller 50 may comprisethe integrated circuit sold by SAMES of South Africa under thedesignation SA9603B. The measurement microcontroller 54 is an SMOS chipavailable under the designation SMC AA316F03.

[0043] The measurement microcontroller 54 also monitors inputs fromtamper switch 56 and disconnect relay 57 for disconnecting the meterfrom the electrical line. The program ROM 59 contains customer specificand site specific variables that may be important for calculatingelectricity usage. The meter 10 has an accuracy of approximately 0.2%for a power input current range of 0-200 amps. Other features that themeasurement microcontroller 54 is able to measure are kilowatt hourusage, voltage and frequency measurements, energy direction, time anddate reporting, load profiling and failure reporting. The power/metercircuit board includes measurement microcontroller 54, level translator52, meter microcontroller 50, backup battery 44, and primary powersupply 32.

[0044] Electric meter 10 is able to communicate commodity utilizationdata and power quality information to a utility over a local areanetwork (LAN) or a wide area network (WAN). A radio frequency (RF)communication section within the electric meter 10 is comprised by acommunication microcontroller and a spread spectrum processor chip 58and a RF transceiver 60. An antenna 62 is coupled to the RF transceiver60 for transmitting and receiving RF spread spectrum signals.

[0045] The communication microcontroller portion of chip 58 isresponsible for all aspects of radio frequency (RF) communicationmanagement in electric meter 10 including determining the presence of avalid interrogating signal from a remotely located gateway node. Thecommunication microcontroller portion of chip 58 provides controlinformation to spread spectrum processor portion of chip 58 and RFtransceiver 60 to control spread spectrum protocol and RFchannelization. Communication microcontroller and spread spectrumprocessor chip 58 may comprise the integrated circuit sold bySiliconians of California, under the designation SS105.

[0046] The spread spectrum communication technique makes use of asequential noise-like signal structure, for example, pseudo-noise (PN)codes to spread a normally narrowband information signal over arelatively wide band of frequencies. This spread spectrum communicationtechnique may be further understood by reference to U.S. Pat. No.5,166,952 and the numerous publications cited therein.

[0047] The use of the spread spectrum communication technique, when usedin conjunction with the direct sequence modulation technique,hereinafter described, gives the LAN data communication system a measureof security. This communication technique also avoids the need to obtainlicensure from governmental authorities controlling radio communication.

[0048] The spread spectrum processor portion of chip 58 functions toperform spread spectrum encoding of the data from communicationmicrocontroller provided to RF transceiver 60 and decoding of the spreadspectrum data from the RF transceiver. A better understanding of thespread spectrum communication technique can be obtained by reading thesubject matter under the subheading entitled “Circuitry of GatewayNode”. The RF transceiver 60 and communication microcontroller andspread spectrum processor chip 58 are part of the circuitry on interfacemanagement unit board 38 and RF module 40 of FIG. 2.

[0049] The meter 10 also includes plugin interface modules whichcorrespond to a variety of different commercially available LAN or WANcommunication devices. These communication devices provide acommunication link directly from the electric meter 10 to a utilityservice provider. For example, shown in FIG. 3, is a narrow bandpersonal communication services (PCS) interface module 64, and a powerline carrier (PLC) interface module 66 powered by a PLC interface powersupply 68. These communication interface modules are easilyinterchangeable within electric meter 10. These modules communicate withthe measurement microcontroller 54 and an interface microcontroller 70along a common backplane or busing system (not shown). Exemplary meterinterface includes the PowerPoint electronic meter interface for the GEKVII meter equipped with an internal antenna, or the GE KVII meterequipped with external antenna. When the meter 10 is configured tomeasure water or aqueous characteristics, a water interface managementunit (“IMU”) interface such as the Silver Spring Network water IMU canbe used. When the meter 10 is configured to measure gaseouscharacteristics, the Silver Spring Network gas IMU is an exemplaryinterface. Other exemplary interfaces include MTC Raven communicationspackage V2.2, Siemens S4 communication package V2.2, or SchlumbergerVectron communication package V2.2.

[0050] Networked Automatic Meter Reading Data Communication System

[0051] In a preferred embodiment of the invention, FIGS. 5 and 6, theelectric meter 10 communicates over a local area network (LAN) 74 to agateway node 72 which transmits the commodity data from the electricmeter 10 to a utility 76 over a fixed common carrier wide area network(WAN) 78. The gateway node 72 provides the end to end communicationlinks from the meter 10 to the utility 76. A first link in the datacommunication system is a two-way 900 MHz spread spectrum LAN 74. Thesecond link within the data communication system is designed to be anycommercially available two-way common carrier WAN 78. In thisembodiment, a gateway node 72 must be within the communication range ofthe electric meter 10 which is approximately one mile.

[0052] In an alternate embodiment, the electric meter 10 provides directlocal area and wide area network access through printed circuit boardsub-assemblies installed in meter 10 described above.

[0053] A more detailed representation of the preferred embodiment isshown in FIGS. 8 and 9A-9E. FIG. 8 shows a functional flow diagram ofthe networked automatic meter reading data communication system of thepresent invention in which the components are described as functionalblocks. The flow diagram FIG. 8, includes the main functional componentsof the gateway note 72 which include a message dispatcher 80, a RFhandler 82, a WAN handler 84, a data stores component 86 and a schedulercomponent 88. The data stores and scheduler components comprise datathat is preprogrammed into the gateway node's memory. The gateway node72 interfaces with the electric meter 10 over the two-way wireless LAN74. The gateway node 72 also interfaces with the utility serviceprovider 76 over the fixed common carrier WAN 78.

[0054]FIG. 9A is a detailed functional diagram of the WAN handler 84 ofFIG. 8. In a typical communication episode, the utility 76 may initiatea request for data from the electric meter 10 by sending a data streamover the WAN 78. The WAN handler 84 of the gateway node 72 receives theWAN data stream, creates a WAN message, verifies the utility ID of thesender from the data stores 86 and routes the WAN message to the messagedispatcher 80 in the gateway node.

[0055] Referring now to FIG. 9B, the message dispatcher 80 receives theWAN message from the WAN handler 84 and determines the request from theutility 76. The message dispatcher 80 determines that the end recipientor target is the electronic meter 10. The message dispatcher 80 thenverifies the meter ID from the data stores 86, creates a RF message androutes the RF message to the RF handler 82.

[0056] Referring now to FIG. 9C, the RF handler 82 receives the RFmessage from the message dispatcher 80, selects a proper RF channel,converts the RF message to a RF data stream, sends the RF data stream tothe electric meter 10 over the LAN 74 and waits for a response. Theelectric meter 10 then responds by sending a RF data stream over the LAN74 to the RF handler 82 of the gateway node 72. The RF handler 82receives the RF data stream, creates a RF message from the RF datastream and routes the RF message to the message dispatcher 80. As shownin FIG. 9B, the message dispatcher 80 receives the RF message,determines the target utility for response from the data stores 86,creates a WAN message and routes the WAN message to the WAN handler 84.The WAN handler 84 receives the WAN message from the message dispatcher80, converts the WAN message to a WAN data stream and sends the WAN datastream to the utility 76 over the fixed common carrier WAN 78, as shownin FIG. 9A to complete the communication episode.

[0057] A communication episode can also be initiated by scheduledreadings preprogrammed into the scheduler 88 of the gateway node asshown in FIG. 9D. A list of scheduled reading times is preprogrammedinto memory within the gateway node 72. The scheduler 88 runsperiodically when a scheduled reading is' due. When it is time for ascheduled reading, the scheduler 88 retrieves meter 10 information fromthe data stores 86, creates a RF message and routes the RF message tothe RF handler 82, receives the RF message, selects a proper RF channel,converts the RF message to a RF data stream, sends the RF data stream tothe electric meter 10 and waits for a response. The meter then respondswith a RF data stream to the RF handler 82. The RF handler 82 receivesthe RF data stream, creates a RF message from the RF data stream androutes the RF message to the message dispatcher 82. The messagedispatcher 80 receives the RF message, determines the target utility forresponse from the data stores 86, creates a WAN message and routes theWAN message to the WAN handler 84. The WAN handler 84 receives the WANmessage, converts the WAN message to a WAN data stream and sends the WANdata stream to the utility 76.

[0058] Occasionally, the utility 76 may request data that is storedwithin the gateway node's memory. In this case, the utility 76 initiatesthe communication episode by sending a WAN data stream to the WANhandler 84. The WAN handler 84 receives the WAN data stream, creates aWAN message, verifies the utility ID of the sender in the data stores 86and routes the WAN message to the message dispatcher 80. As shown inFIG. 15B, the message dispatcher 80 receives the WAN message anddetermines the request from the utility 76. The message dispatcher 80then determines the target of the message. If the data requested isstored in the gateway node memory, then the gateway node 72 performs therequested task, determines that the requesting utility is the targetutility for a response, creates a WAN message and routes the WAN messageto the WAN handler 84. The WAN handler 84 receives the WAN message,converts the WAN message to a WAN data stream and sends the WAN datastream to the utility 76.

[0059] The last type of communication episode is one which is initiatedby the electric meter 10. In this case, the meter detects an alarmoutage or tamper condition and sends a RF data stream to the RF handler82 of the gateway node 72. The RF handler 82 receives the RF datastream, creates a RF message from the RF data stream and routes the RFmessage to the message dispatcher 80. The message dispatcher 80 receivesthe RF message, determines the target utility for response from the datastores 86, creates a WAN message and routes the WAN message to the WANhandler 84. The WAN handler 84 receives the WAN message, converts theWAN message to a WAN data stream and sends the WAN data stream to theutility 76.

[0060] There are thus three different types of communication episodesthat can be accomplished within the automatic meter reading datacommunication system shown in FIGS. 8 and 9A-E. The automatic meterreading functions incorporated in electric meter 10 include monthlyusage readings, demand usage readings, outage detection and reporting,tamper detection and notification, load profiling, first and final meterreadings, and virtual shutoff capability.

[0061]FIG. 9D represents information or data that is preprogrammed intothe gateway node's memory. Included within the memory is a list ofscheduled reading times to be performed by the interface managementunit. These reading times may correspond to monthly or weekly usagereadings, etc.

[0062]FIG. 9E represents data or information stored in the gatewaynode's memory dealing with registered utility information and registeredinterface management unit information. This data includes the utilityidentification numbers of registered utilities, interface managementunit identification numbers of registered interface management units,and other information for specific utilities and specific interfacemanagement units, so that the gateway node may communicate directly withthe desired utility or correct electric meter.

[0063] Electronic Electric Meter Virtual Shut-Off Function

[0064] The virtual shut-off function of the electric meter 10 is usedfor situations such as a change of ownership where a utility service isto be temporarily inactive. When a residence is vacated there should notbe any significant consumption of electricity at that location. If thereis any meter movement, indicating unauthorized usage, the utility needsto be notified. The tamper switch 56 of the electric meter 10 provides ameans of flagging and reporting meter movement beyond a preset thresholdvalue.

[0065] Activation of the virtual shut-off mode is accomplished throughthe “set virtual threshold” message, defined as a meter count which theelectric meter is riot to exceed. In order to know where to set thethreshold it is necessary to know the present meter count. The gatewaynode reads the meter count, adds whatever offset is deemed appropriate,sends the result to the electric meter as a “set virtual shut-off”message. The electric meter will then enable the virtual shut-offfunction. The electric meter then accumulates the meter counts. If themeter count is greater than the preset threshold value then the electricmeter sends a “send alarm” message to the gateway node until a “clearerror code” message is issued in response by the gateway node. However,if the meter count is less than the preset threshold value then theelectric meter continues to monitor the meter count. The virtualshut-off function may be canceled at any time by a “clear error code”message from the gateway node.

[0066] If the meter count in the meter does not exceed the presetthreshold value at any given sampling time, then the meter continues tocount until the preset threshold count is attained or until operation inthe virtual shut-off mode is canceled.

[0067] Gateway Node

[0068] The gateway node 72 is shown in FIG. 4. The gateway node 72 istypically located on top of a power pole or other elevated location sothat it may act as a communication node between LAN 74 and WAN 78. Thegateway node 72 includes an antenna 90 for receiving and transmittingdata over the RF communication links, and a power line carrier connector92 for connecting a power line to power the gateway node 72. The gatewaynode 72 may also be solar powered. The compact design allows for easyplacement on any existing utility pole or similarly situated elevatedlocation. The gateway node 72 provides end to end communications fromthe meter 10 to the utility 76. The wireless gateway node 72 interfaceswith the electric meter 10 over a two-way wireless 900 MHz spreadspectrum LAN 74. Also, the gateway node 72 will interface and becompatible with any commercially available WAN 78 for communicatingcommodity usage and power quality information with the utility. Thegateway node 72 is field programmable to meet a variety of datareporting needs.

[0069] The gateway node 72 receives data requests from the utility,interrogates the meter and forwards commodity usage information, as wellas power quality information, over the WAN 78 to the utility 76. Thegateway node 72 exchanges data with certain, predetermined, meters forwhich it is responsible, and “listens” for signals from those meters.The gateway node 72 does not store data for extended periods, thusminimizing security risks. The gateway node's RF communication range istypically one mile.

[0070] A wide variety of fixed wide area network (WAN) communicationsystems such as those employed with two-way pagers, cellular telephones,conventional telephones, narrowband personal communication services(PCS); cellular digital packet data (CDPD) systems, and satellites maybe used to communicate data between the gateway nodes and the utility.The data communication system utilizes channelized direct sequence 900MHz spread spectrum transmissions for communicating between the metersand gateway nodes. An exemplary gateway node includes the Silver SpringNetwork Gateway node that uses the AxisPortal V2.2 and common carrierwide area networks such as telephone, code-division multiple access(“CDMA”) cellular networks. Other exemplary gateway node includes theSilver Spring Network AxisGate Network Gateway.

[0071] Circuitry of Gateway Node

[0072]FIG. 7 shows a block diagram of the gateway node circuitry. The RFtransceiver section 94 of gateway node 72 is the same as the RFtransceiver section 60 of electric meter 10 and certain portionsthereof, such as the spread spectrum processor and frequencysynthesizer, are shown in greater detail in FIG. 7. The gateway node 72includes a WAN interface module 96 which may incorporate electroniccircuitry for a two-way pager, power line carrier (PLC), satellite,cellular telephone, fiber optics, cellular digital packet data (CDPD)system, personal communication services (PCS), or other commerciallyavailable fixed wide area network (WAN) system. The construction of WANinterface module 96 and initialization microcontroller 98 may changedepending on the desired WAN interface. RF channel selection isaccomplished through a RF channel select bus 100 which interfacesdirectly with the initialization microcontroller 98.

[0073] Initialization microcontroller 98 controls all node functionsincluding programming spread spectrum processor 102, RF channelselection in frequency synthesizer 104 of RF transceiver 94,transmit/receive switching, and detecting failures in WAN interfacemodule 96.

[0074] Upon power up, initialization microcontroller 98 will program theinternal registers of spread spectrum processor 102, read the RF channelselection from the electric meter 10, and set the system forcommunication at the frequency corresponding to the channel selected bythe meter 10.

[0075] Selection of the RF channel used for transmission and receptionis accomplished via the RF channel select bus 100 to initializationmicrocontroller 98. Valid channel numbers range from 0 to 23. In orderto minimize a possibility of noise on the input to initializationmicrocontroller 98 causing false channel switching, the inputs have beendebounced through software. Channel selection data must be present andstable on the inputs to initialization microcontroller 98 forapproximately 250 μs before the initialization microcontroller willaccept it and initiate a channel change. After the channel change hasbeen initiated, it takes about 600 μs for frequency synthesizer 104 ofRF transceiver 94 to receive the programming data and for theoscillators in the frequency synthesizer to settle to the changedfrequency. Channel selection may only be completed while gateway node 72is in the receive mode. If the RF channel select lines are changedduring the transmit mode the change will not take effect until after thegateway node has been returned to the receive mode.

[0076] Once initial parameters are established, initializationmicrocontroller 98 begins its monitoring functions. When gateway node 72is in the receive mode, the initialization microcontroller 98continuously monitors RF channel select bus 100 to determine if achannel change is to be implemented.

[0077] For receiving data, gateway node 72 monitors the electric meter10 to determine the presence of data. Some additional handshakinghardware may be required to sense the presence of a spread spectrumsignal.

[0078] An alarm message is sent automatically by electric meter 10 inthe event of a tamper or alarm condition, such as a power outage. Themessage is sent periodically until the error has cleared. Gateway node72 must know how many bytes of data it is expecting to see and countthem as they come in. When the proper number of bytes is received,reception is deemed complete and the message is processed. Any deviationfrom the anticipated number of received bytes may be assumed to be anerroneous message.

[0079] During the transmit mode of gateway node 72, initializationmicrocontroller 98 monitors the data line to detect idle conditions,start bits, and stop bits. This is done to prevent gateway node 24 fromcontinuously transmitting meaningless information in the event a failureof WAN interface module 96 occurs and also to prevent erroneous trailingedge data from being sent which cannot terminate transmissions in atimely fashion. The initialization microcontroller 98 will not enable RFtransmitter 106 of RF transceiver 94 unless the data line is in theinvalid idle state when communication is initiated.

[0080] A second watchdog function of initialization micro-controller 98when gateway node 72 is in the transmit mode is to test for valid startand stop bits in the serial data stream being transmitted. This ensuresthat data is read correctly. The first start bit is defined as the firstfalling edge of serial data after it has entered the idle stage. Allfurther timing during that communication episode is referenced from thatstart bit. Timing for the location of a stop bit is measured from theleading edge of a start bit for that particular byte of data.Initialization microcontroller 98 measures an interval which is 9.5 bittimes from that start bit edge and then looks for a stop bit. Similarly,a timer of 1 bit interval is started from the 9.5 bit point to look forthe next start bit. If the following start bit does not assert itselfwithin 1 bit time of a 9.5 bit time marker a failure is declared. Theresponse to a failure condition is to disable RF transmitter 106.

[0081] Communication to and from electric meter 10 may be carried out inone of a preselected number, for example 24 channels in a preselectedfrequency band, for example 902-928 MHz. The meter 10 receives data andtransmits a response on a single RF channel which is the same for bothtransmit and receive operation. As hereinafter described, the specificRF channel used for communication is chosen during commissioning andinstallation of the unit and loaded into memory. The RF channel ischosen to be different from the operating channels of other, adjacentinterface management units, thereby to prevent two or more interfacemanagement units from responding to the same interrogation signal.

[0082] Frequency synthesizer 104 performs the modulation anddemodulation of the spread spectrum data provided by spread spectrumprocessor 60 onto a carrier signal and demodulation of such data fromthe carrier signal. The RF transceiver has separate transmitter 106 andreceiver 108 sections fed from frequency synthesizer 104.

[0083] The output of the spread spectrum processor to frequencysynthesizer comprises a 2.4576 MHz reference frequency signal inconductor and a PN encoded base band signal in conductor. Frequencysynthesizer may comprise a National Semiconductor LMX2332A DualFrequency Synthesizer.

[0084] The direct sequence modulation technique employed by frequencysynthesizer uses a high rate binary code (PN code) to modulate the baseband signal. The resulting spread signal is used to modulate thetransmitter's RF carrier signal. The spreading code is a fixed length PNsequence of bits, called chips, which is constantly being recycled. Thepseudo-random nature of the sequence achieves the desired signalspreading, and the fixed sequence allows the code to be replicated inthe receiver for recovery of the signal. Therefore, in direct sequence,the base band signal is modulated with the PN code spreading function,and the carrier is modulated to produce the wide band signal.

[0085] Minimum shift keying (MSK) modulation is used in order to allowreliable communications, efficient use of the radio spectrum, and tokeep the component count and power consumption low. The modulationperformed by frequency synthesizer 72 is minimum shift keying (MSK) at achip rate of 819.2 Kchips per second, yielding a transmission with a 6dB instantaneous bandwidth of 670.5 KHz.

[0086] The receiver bandwidth of this spread spectrum communicationtechnique is nominally 1 MHz, with a minimum bandwidth of 900 KHz.Frequency resolution of the frequency synthesizer is 0.2048 MHz, whichwill be used to channelize the band into 24 channels spaced a minimum of1.024 MHz apart. This frequency channelization is used to minimizeinterference between interface management units within a commoncommunication range as well as providing growth for future, advancedfeatures associated with the data communication system.

[0087] Frequency control of the RF related oscillators in the system isprovided by dual phase locked loop (PLL) circuitry within frequencysynthesizer. The phase locked loops are controlled and programmed byinitialization microcontroller via a serial programming control bus,FIG. 7. The frequency synthesizer produces two RF signals which aremixed together in various combinations to produce a transmission carrierand to demodulate incoming RF signals. The transmission carrier is basedon frequencies in the 782-807 MHz range and the demodulation signal isbased on frequencies in the 792-817 MHz range. These signals may bereferred to as RF transmit and RF receive local oscillation signals.

[0088] Table 1 below is a summary of the transmission channelfrequencies and associated frequency synthesizer transmit/receiveoutputs. The signals in the table are provided by the two PLL sectionsin the dual frequency synthesizer. TABLE 1 Channel Channel TransmitLocal Receive Local Number Frequency (MHz) Oscillation (MHz) Oscillation(MHz) 0 902.7584 782.3360 792.1664 1 903.7824 783.3600 793.1904 2904.8064 784.3840 794.2144 3 905.8304 785.4080 795.2384 4 906.8544786.4320 796.2624 5 907.8784 787.4560 797.2864 6 908.9024 788.4800798.3104 7 910.1312 789.7088 799.5392 8 911.1552 790.7328 800.5632 9912.1792 791.7568 801.5872 10 913.2032 792.7808 802.6112 11 914.2272793.8048 803.6352 12 915.2512 794.8288 804.6592 13 916.2752 795.8528805.6832 14 917.2992 796.8768 806.7072 15 918.3232 797.9008 807.7312 16919.9616 799.5392 809.3696 17 920.9856 800.5632 810.3936 18 922.0096801.5872 811.4176 19 923.2384 802.8160 812.6464 20 924.2624 803.8400813.6704 21 925.2864 804.8640 814.6944 22 926.3104 805.8880 815.7184 23927.3344 806.9120 816.7424

[0089] A third signal, which is fixed at 120.4224 MHz, is also suppliedby the dual frequency synthesizer. This signal is referred to as theintermediate frequency (IF) local oscillation signal.

[0090] In transmission mode, frequency synthesizer 104 provides a signalhaving a frequency in the 782-807 MHz range, modulated with the data tobe transmitted. RF transmitter section 106 mixes the signal with thefixed frequency IF local oscillator signal. This results in a RF signalwhich ranges between 902 MHz and 928 MHz. The signal is filtered toreduce harmonics and out of band signals, amplified and supplied toantenna switch 110 and antenna 112.

[0091] It is recognized that other equivalents, alternatives, andmodifications aside from those expressly stated, are possible and withinthe scope of the appended claims.

1. A metering system for measuring a commodity characteristic andreporting the commodity characteristic to a commodity receiver, thesystem comprising: a first meter having a first transducer operable tosense the commodity characteristic and generate data representative ofthe commodity characteristic, and a communication section operable totransmit the data from the first meter; and a second meter having asecond communication section configured to relay the data from the firstmeter to the commodity receiver or a subsequent meter.
 2. The system ofclaim 1, and wherein the data further comprises a data targetidentification, a target request, and a target reply.
 3. The system ofclaim 1, and wherein each of the meters further comprises a meteridentification, and wherein the commodity receiver comprises a commodityreceiver identification.
 4. The system of claim 3, and wherein each ofthe meters further comprises a data target identification, wherein ameter becomes a data target when the data target identification matchesthe meter identification, and wherein the commodity receiver becomes adata target when the data target identification matches the commodityreceiver identification.
 5. The system of claim 1, and wherein each ofthe meters further comprises a level translator operatively to conditionthe data.
 6. The system of claim 1, and wherein the second meter furthercomprises a second transducer, and wherein the transducer furthercomprises a voltage interface transducer.
 7. The system of claim 1, andwherein the second meter further comprises a second transducer, andwherein the further comprises a current interface transducer.
 8. Thesystem of claim 1, and wherein each of the meters further comprises acontroller, and wherein each of the meters further comprises a displayoperable to be coupled to each of the controller to display the data. 9.The system of claim 1, and wherein each of the meters further comprisesan antenna operatively coupled to the communication section to transmitand receive.
 10. The system of claim 1, and wherein each of thecommunication sections further comprises a spread spectrum processor tospectrally spread a radio frequency signal.
 11. The system of claim 10,and wherein each of the communication sections further comprises atransceiver to transmit and receive a spectrally spread signal over alocal area network.
 12. The system of claim 11, and wherein thetransceiver further comprises a frequency synthesizer operable togenerate a carrier signal, the carrier signal to be modulated by thespectrally spread signal.
 13. The system of claim 1, and wherein each ofthe meters further comprises a plug-in interface module operativelycoupled to the communication section to communicate with a networkdevice.
 14. The system of claim 13, and wherein the network devicecomprises a local area network device.
 15. The system of claim 13, andwherein the network device comprises a common carrier wide area networkdevice.
 16. The system of claim 1, and the commodity receiver comprisesa gateway node.
 17. The system of claim 1, and wherein the commodityreceiver comprises a utility provider.
 18. The system of claim 1, andwherein each of the meters is an electric meter.
 19. A metering systemfor measuring a commodity characteristic and reporting the commoditycharacteristic to a commodity receiver, the system comprising: a firstmeter having a first transducer means for sensing the commoditycharacteristic and generating data representative of the commoditycharacteristic, and a communication means for transmitting the data fromthe first meter; and a second meter having a second communicationsection configured to relay the data from the first meter to thecommodity receiver or a subsequent meter.
 20. The system of claim 19,and wherein the data further comprises a data target identification, atarget request, and a target reply.
 21. The system of claim 19, andwherein each of the meters further comprises a meter identification, andwherein the commodity receiver comprises a commodity receiveridentification.
 22. The system of claim 21, wherein each of the metersfurther comprises a data target identification, wherein a meter becomesa data target when the data target identification matches the meteridentification, and wherein the commodity receiver becomes a data targetwhen the data target identification matches the commodity receiveridentification.
 23. The system of claim 19, and wherein each of themeters further comprises a level translator for conditioning the data.24. The system of claim 19, and wherein the second meter furthercomprises a second transducer, and wherein the transducer furthercomprises a voltage interface transducer.
 25. The system of claim 19,and wherein the second meter further comprises a second transducer, andwherein the further comprises a current interface transducer.
 26. Thesystem of claim 19, and wherein each of the meters further comprises acontroller, and wherein each of the meters further comprises a displayoperable to be coupled to each of the controller for displaying thedata.
 27. The system of claim 19, and wherein each of the meters furthercomprises an antenna operatively coupled to the communication sectionfor transmitting and receiving.
 28. The system of claim 19, and whereineach of the communication sections further comprises a spread spectrumprocessor for spectrally spreading a radio frequency signal.
 29. Thesystem of claim 28, and wherein each of the communication sectionsfurther comprises a transceiver for transmitting and receiving aspectrally spread signal over a local area network.
 30. The system ofclaim 29, and wherein the radio frequency transceiver further comprisesa frequency synthesizer for generating a carrier signal, the carriersignal to be modulated by the spectrally spread signal.
 31. The systemof claim 19, and wherein each of the meters further comprises a plug-ininterface module operatively coupled to the communication section forcommunicating with a network device.
 32. The system of claim 31, andwherein the network device comprises a local area network device. 33.The system of claim 31, and wherein the network device comprises acommon carrier wide area network device.
 34. The system of claim 19, andthe commodity receiver comprises a gateway node.
 35. The system of claim19, and wherein the commodity receiver comprises a utility provider. 36.The system of claim 19, and wherein each of the meters is an electricmeter.
 37. A method of relaying data representative of a commoditycharacteristic, the method comprising the acts of: generating data usingthe commodity characteristic at a first meter; transmitting the datawith a first transceiver from the first meter; receiving the data fromthe first meter at a second meter; and transmitting the data using thesecond meter to a remote commodity receiver or a third meter.
 38. Themethod of claim 37, further comprising the acts of transmitting andreceiving the data over a network.
 39. The method of claim 37, furthercomprising the act of conditioning the commodity characteristic.
 40. Themethod of claim 37, and wherein the commodity characteristics comprisesa voltage level, the method further comprising the acts of sensing thevoltage level with a voltage transducer.
 41. The method of claim 37, andwherein the commodity characteristics comprises a current level, themethod further comprising the acts of sensing the current level with acurrent transducer.
 42. The method of claim 37, further comprising theact of displaying the processed commodity characteristic.
 43. The methodof claim 37, further comprising the acts of transmitting and receivingthe data with an antenna.
 44. The method of claim 37, further comprisingthe act of spectrally spreading a radio frequency signal based on thecommodity characteristic.
 45. The method of claim 44, further comprisingthe acts of transmitting and receiving a spectrally spread signal. 46.The method of claim 45, further comprising the acts of transmitting andreceiving the spectrally spread signal over a local area network. 47.The method of claim 46, further comprising the act of generating acarrier signal to be modulated by the spectrally spread signal.
 48. Themethod of claim 37, further comprising the acts of: providing the metera plug-in interface; and transmitting and receiving with a networkdevice via the plug-in interface.
 49. The method of claim 48, furthercomprising the acts of transmitting and receiving with a local areanetwork device.
 50. The method of claim 48, further comprising the actsof transmitting and receiving with a common carrier wide area networkdevice.
 51. The method of claim 37, and wherein each of the meters is anelectric meter.
 52. A meter relay system comprising: a commoditytransceiver; and a plurality of meters including at least one meterbeing a target meter, each meter having a transducer operable to sense acommodity characteristic and generate data representative of thecommodity characteristic, and each meter having a communication sectionoperable to receive a request from the commodity transceiver and from anadjacent meter, to transmit the request to an adjacent meter until therequest reaches the target meter, to receive the data from an adjacentmeter, and to transmit the data to an adjacent meter and to thecommodity transceiver.
 53. The system of claim 52, and wherein the datafurther comprises a target meter identification.
 54. The system of claim52, and wherein each of the meters further comprises a meteridentification, and wherein the commodity transceiver comprises acommodity identification.
 55. The system of claim 54, and wherein thedata further comprises a target identification, wherein a meter becomesa target meter when the target identification matches the meteridentification, and wherein a commodity transceiver becomes a targetmeter when the target identification matches the commodityidentification.
 56. The system of claim 52, and wherein each of themeters further comprises a level translator operatively to condition thedata.
 57. The system of claim 52, and wherein the transducer furthercomprises a voltage interface transducer.
 58. The system of claim 52,and wherein the transducer further comprises a current interfacetransducer.
 59. The system of claim 52, and wherein each of the metersfurther comprises a controller, and wherein each of the meters furthercomprises a display operable to be coupled to each of the controller todisplay the data.
 60. The system of claim 52, and wherein each of themeters further comprises an antenna operatively coupled to thecommunication section to transmit and receive.
 61. The system of claim52, and wherein each communication section further comprises a spreadspectrum processor to spectrally spread a radio frequency signal. 62.The system of claim 61, and wherein each communication section furthercomprises a radio frequency transceiver to transmit and receive aspectrally spread signal over a local area network.
 63. The system ofclaim 62, and wherein the radio frequency transceiver further comprisesa frequency synthesizer operable to generate a carrier signal to bemodulated by the spectrally spread signal.
 64. The system of claim 52,and wherein each of the meters further comprises a plug-in interfacemodule operatively coupled to the communication section to communicatewith a network device.
 65. The system of claim 64, and wherein thenetwork device comprises a local area network device.
 66. The system ofclaim 64, and wherein the network device comprises a common carrier widearea network device.
 67. The system of claim 52, and the commoditytransceiver comprises a gateway node.
 68. The system of claim 52, andwherein the commodity transceiver comprises a utility provider.
 69. Thesystem of claim 52, and wherein at least one of meters is an electricmeter.